Rapid thermal processing chamber with micro-positioning system

ABSTRACT

Methods and apparatus for rapid thermal processing of a planar substrate including axially aligning the substrate with a substrate support or with an empirically determined position are described. The methods and apparatus include a sensor system that determines the relative orientations of the substrate and the substrate support.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional under 35 U.S.C. §120 of U.S. patentapplication Ser. No. 12/611,958, filed Nov. 4, 2009 which claimspriority under 35 U.S.C. §119(e) of U.S. Provisional Patent ApplicationNo. 61/112,008, filed Nov. 6, 2008 and U.S. Provisional PatentApplication No. 61/112,015, filed Nov. 6, 2008.

TECHNICAL FIELD

Methods and associated apparatus for rapid thermal processing ofsubstrates are disclosed. More specifically, apparatus and methods forrapid thermal processing of substrates including a micro-positioningsystem are disclosed.

BACKGROUND

Integrated circuits have evolved into complex devices that can includemillions of transistors, capacitors and resistors on a single chip. Theevolution of chip design requires faster circuitry and greater circuitdensity that demand increasingly precise fabrication processes.

Rapid thermal processing (RTP) generally includes heating from a radiantheat source, such as lamps and/or resistive heating elements. In aconventional RTP system, the substrate is heated to a desiredtemperature, and then the radiant heat source is turned off, whichcauses the substrate to cool. In some systems, a gas may flow onto thesubstrate to enhance cooling. However, as processing parameters continueto evolve, temperature ramp up and heating uniformity during RTPrequires closer monitoring and control.

A frequently used process for treating substrates (also referred toherein as “wafers”) is ion implantation. Ion implantation typicallytakes the substrates through a thermal process performed in a rapidthermal processing (RTP) chamber that provides a uniformly distributedthermal cycle that can heat the substrate from room temperature toapproximately 450° C. to about 1400° C. In a conventional RTP system,robotic arm is used to transfer substrates to a structure that supportsthe substrates in the RTP chamber. The substrates need to be placed onthe center of the structure to promote even heat distribution across thesubstrate surface. However, when substrates are transferred onto thestructure, it is often that the positioning of the substrate on the ringstructure cannot be accurately repeated. For example, the robotic armmay not be able to position consecutive substrates onto the samecentered position on the structure. The difference in the positioning ofthe substrates may lead to uneven heat distribution across the substratesurface, therefore a decrease in production of the substrate.

Some rapid thermal processing apparatus use a substrate support in theform of an “edge ring” to support the substrate or wafer. As the nameimplies, the edge ring holds the substrate, typically called a wafer,around the edges only so as to minimize the contact with the substrate.If the wafer is not centered on the edge ring or other wafer support,uneven overlap on either side of the wafer create a side to sidenon-uniformity that rotates with the wafer (and wafer support). Robotplacement accuracy is limited to ±0.007 inches. However, for every 0.001inch that the wafer is placed off-center of the wafer support, the wafercan experience a 1° C. side-to-side temperature difference. Thus, inorder to achieve temperature uniformity in the range of ±2° C., thewafer needs to be placed on the wafer support such that the wafer andwafer support are coaxial within ±0.002 inches.

Therefore, there is a need in the art for apparatuses and methods forthe micro-positioning of a substrate or for precision control of thesubstrate on a wafer support in a rapid thermal processing chamber.

SUMMARY

Aspects of this invention involve the use of micro-positioning systemsto coaxially align a substantially flat substrate with a substratesupport in a rapid thermal processing chamber. This allows for moreuniform heating across the substrate during processing.

According to one or more embodiments, it is possible to center the waferon the substrate support by adjusting the position of one or more of thewafer, substrate support or an optional magnetically levitated rotor sothe wafer is substantially coaxial with the substrate support. Thesubstrate location with respect to the substrate support can bemonitored by the position sensor systems which can provide feedback to apositioning mechanism to accurately and reproducibly achieve coaxialalignment of the substrate and substrate support.

In one embodiment, a rapid thermal processing apparatus for processingplanar substrates comprises a chamber with a heat source and a firstsubstrate support for holding the substrate in the chamber in a firstposition. A second substrate support, in a second position, is in thechamber for holding the substrate. In one embodiment, the secondsubstrate support holds the substrate at the periphery during thermalprocessing. The second substrate support is moveable in a direction toplace the substrate support closer or further from the heat source. Asensor to sense the position of the substrate relative to the secondsubstrate support communicates with an actuator to change the positionof the substrate relative to the position of the second substratesupport within the plane of the substrate. As used herein, “within theplane of the substrate” refers to a plane substantially parallel to theflat surface of the substrate, for example, as in the x-y plane of aCartesian coordinate system.

The sensor can be configured in a variety of ways. The sensor accordingto one or more embodiments includes an optical detector. The opticaldetector may include a light source to direct a light beam onto asurface of the substrate. The system may also include a detectorpositioned to monitor the intensity of light reflected from thesubstrate in response to the light beam. One or both the detector andthe substrate may be moveable to provide relative motion between thedetector and the substrate. In some embodiments, the sensor furthercomprises an electronic controller in communication with the detector,wherein the controller generates a plurality of measurements fromreflections detected by the detector and calculates a location on thesubstrate surface where a reflection occurred, including determiningwhich of the measurements corresponds to an edge of the substrate.

In some embodiments, the optical detector evaluates a shadow cast byeither the second substrate support on the substrate or the substrate onthe second substrate support to detect the position of the substraterelative to the position of the second substrate support.

An alternative sensor comprises a camera, an illumination system and avision image analysis system which detects the centers of the secondsubstrate support and substrate. In other embodiments, the sensorevaluates a shadow cast by either the substrate support onto thesubstrate, or the substrate onto the substrate support, to detect theposition of the substrate relative to the position of the substratesupport.

In a detailed embodiment, the first substrate support is selected from arobot blade and a lift pin assembly and the second substrate support isan edge ring. In specific embodiments, the chamber further comprises achamber lid and at least two position sensors. The at least two positionsensors being located on the chamber lid. A reflective light beam mayoptionally be transmitted from the at least two sensors through thechamber lid.

In some embodiments, the chamber further comprises liquid or gas jetspositioned adjacent the substrate to move the substrate in a pluralityof directions.

In various embodiments, the chamber further comprises a plurality ofpositioning rods oriented in the same plane as the substrate, thepositioning rods being adapted to contact the edge of the substrate topush the substrate in a plurality of directions within the plane of thesubstrate.

Further embodiments comprise a mechanism adapted to move the substratein a plurality of directions within the plane of the substrate. In someembodiments this is done by a plurality of positioning rods oriented inthe same plane as the substrate, substrate support or a magneticallylevitated rotor. The positioning rods are positioned to contact the edgeof the substrate, substrate support or the magnetically levitated rotor.The rods being capable of pushing the substrate in a plurality ofdirections, for example in a plurality of directions parallel to theplane of the substrate.

According some embodiments, the substrate support is coupled to amagnetically levitated rotor. In detailed embodiments, the magneticallylevitated rotor can be moved in a plurality of directions parallel planeof the substrate. In one or more embodiments, the magnetically levitatedrotor is coupled to mechanism comprising a magnetic field generatingdevice adapted to create a magnetic field coupled to the magneticallylevitated rotor, the magnetic field being modifiable to move thelevitated rotor in a plurality of directions parallel to the plane ofthe substrate.

According to some detailed embodiments, the chamber further comprises amagnetic field generating device coupled to the magnetically levitatedrotor. The magnetic field being modifiable to move the levitated rotorin a plurality of axial directions within the plane of the substrate.

In some detailed embodiments, the chamber further comprises a systemcontroller to obtain position signals from the sensor and to send asignal to one or more electromagnets to adjust the position of thesecond substrate support relative to the substrate.

In some specific embodiments, the second substrate support comprises anedge ring including an alignment mark on an inner surface of thesubstrate support to be aligned with a corresponding alignment mark onthe substrate.

In one or more embodiments, the first substrate support comprises liftpins for transferring the substrate between a loading blade and thesecond substrate support. The lift pins may be adapted to pass throughopening in the substrate support and contact and lift the substrate. Insome embodiments, a mechanism adapted to move the lift pins within thesubstrate support holes without moving the axial position of thesubstrate support is incorporated.

The apparatus of one or more detailed embodiments is capable ofaccurately and reproducibly positioning the substrate support andsubstrate within about ±0.005 inches of being coaxial. In more detailedembodiments, the substrate and substrate support are positioned to bewithin about ±0.002 inches of being coaxial, or within about ±0.001inches of being coaxial.

Another aspect of the invention is directed to a method of processing asubstrate. The method comprises transferring a substrate into aprocessing chamber. The substrate is transferred to a set of lift pins.The location of the edge of the substrate is determined. The position ofthe substrate relative to a substrate support is adjusted so that thesubstrate and the substrate support are coaxial. The substrate istransferred to the substrate support. The substrate is then ready to beprocessed.

The order of these steps varies depending on the particular embodimentof use and should not be taken as a strict procedural sequence. In someembodiments, the relative position of the substrate with respect to thesubstrate support is adjusted prior to transferring the substrate ontothe lift pins. In other embodiments, the relative position with respectto the substrate support is adjusted after transferring the substrate tothe lift pins. In various embodiments, the relative position of thesubstrate with respect to the substrate support is adjusted by changingone or more of the location of the substrate, the location of the edgering or the location of the lift pins.

One or more embodiments of the invention are directed to methods ofprocessing a substrate. A planar substrate having an edge is transferredinto a processing chamber onto an intermediate substrate support. Thelocation of the edge of the substrate is determined. The position of thesubstrate relative to a second substrate support is adjusted so that thesubstrate and the second substrate support are in substantially centeredorientation. The substrate is transferred to the second substratesupport and the substrate is processed.

In detailed embodiments, the substrate is transferred into theprocessing chamber on a robot blade. The intermediate substrate supportmay comprise lift pins and the relative position of the substrate withrespect to the second substrate support may be adjusted prior totransferring the substrate onto the lift pins.

In detailed embodiments, the relative position of the substrate withrespect to the second substrate support may be adjusted by changing oneor more of the location of the substrate, the location of the secondsubstrate support or the location of the intermediate substrate support.

In some specific embodiments, the methods further comprise transmittinga reflective light beam from one sensor through a space between thesubstrate and the substrate support to determine a theta adjustmentvalue for placing the substrate onto a center position of the secondsubstrate support. In further detailed embodiments, the theta adjustmentvalue is determined by measuring a distance from at least two positionsX and Y between the second substrate support and the substrate and atleast two sensors are used to determine the distance from the at leasttwo positions X and Y for the theta adjustment.

In one or more embodiments, the position of the second substrate supportis adjusted by applying one or more magnetic fields adjacent thesubstrate support. According to detailed embodiments, one or moresensors are in communication with a control system in communication witha plurality of magnets adjacent the substrate support, and the magneticfields are applied in response to a position obtained by a sensor.

Although the foregoing refers to coaxial positioning, the invention(s)disclosed herein are not limited to coaxial positioning and may be usedto position the substrate relative to the substrate support in anyprescribed amount of axial position (for example, within ±7 mm) and anydesired prescribed r, theta position. The geometric center of thesubstrate may not be the thermal center of the substrate. Also, due tovariability of the substrate support, an optimum position (r, theta) maybe determined for best thermal processing reproducibility, even thoughthe wafer is not physically coaxial with the substrate support. Thus,embodiments of the invention can be used to ensure that the wafer isoptimally positioned, even if that position is not physically coaxialwith the substrate support.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a simplified isometric view of a rapid thermal processingchamber according to an embodiments of the invention;

FIG. 2A shows a partial side view of a positioning system with a sensorsystem for sensing the position of the substrate according to oneembodiment;

FIG. 2B shows a partial side view of a positioning system with sensorsystem for sensing the position of the substrate according to oneembodiment;

FIG. 3A shows a partial side view of a positioning system according toone embodiment;

FIG. 3B shows a partial side view of a positioning system according toone embodiment;

FIG. 3C shows a partial perspective view of a positioning systemaccording to one embodiment;

FIG. 4 shows a partial perspective view of a chamber according to anembodiment of the invention;

FIG. 5 shows a partial perspective view of a chamber according to anembodiment of the invention;

FIG. 6 shows a partial perspective view of a chamber according to anembodiment of the invention;

FIG. 7 shows a side view of a positioning mechanism according to one ormore embodiments of the invention;

FIG. 8A shows a side view of an embodiment of a positioning mechanism;

FIG. 8B shows a side view of an embodiment of a positioning mechanism;

FIG. 9A is a top view of a substrate support according to one or moreembodiment of the invention;

FIG. 9B is a cross sectional view of a substrate support according toone or more embodiment of the invention;

FIG. 9C is a schematic drawing of an edge ring according to one or moreembodiment of the invention;

FIG. 10A is a top view of a substrate support within a processingchamber according to one or more embodiment of the invention;

FIG. 10B is a cross sectional view between the edge ring of a substratesupport and a substrate according to one or more embodiment of theinvention;

FIG. 10C is a top view of a substrate support within a processingchamber according to one or more embodiment of the invention;

FIG. 11 is a simplified isometric view of a rapid thermal processingchamber according to one or more embodiment of the invention; and

FIG. 12 is a top view of a stator assembly with the housing removedaccording to one or more embodiments of the invention.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the invention, it isto be understood that the invention is not limited to the details ofconstruction or process steps set forth in the following description.The invention is capable of other embodiments and of being practiced orbeing carried out in various ways.

The embodiments described below are generally directed to a RTP systemincluding a micro-positioning system to axially align the substrate andthe substrate support within the plane of the substrate. As used herein,rapid thermal processing or RTP refers an apparatus or a process capableof uniformly heating a wafer at rates of about 50° C./second and higher,for example, at rates of 100 to 150° C./second, and 200 to 400°C./second. Typical ramp-down (cooling) rates in RTP chambers are in therange of 80-150° C./second. Some processes performed in RTP chambersrequire variations in temperature across the substrate of less than afew degrees Celsius. Thus, an RTP chamber might include a lamp or othersuitable heating system and heating system control capable of heating atrates of up to 100 to 150° C./second, and 200 to 400° C./seconddistinguishing rapid thermal processing chambers from other types ofthermal chambers that do not have a heating system and heating controlsystem capable of rapidly heating at these rates. In the embodimentshown, the RTP chamber optionally includes a substrate support that isadapted to levitate and rotate within the chamber without any contactwith the inside walls of the chamber.

Referring now to FIG. 1, an exemplary embodiment of a rapid thermalprocessing chamber 100 is shown. The processing chamber 100 includes asubstrate support 104, a chamber body 102, having walls 108, a bottom110, and a top or lid 112 defining an interior volume 120. The walls 108typically include at least one substrate access port 148 to facilitateentry and egress of a substrate 140 (a portion of which is shown in FIG.1). The access port may be coupled to a transfer chamber (not shown) ora load lock chamber (not shown) and may be selectively sealed with avalve, such as a slit valve (not shown), which seals the interior volume120 from the surrounding atmosphere. In one embodiment, the substratesupport 104 is annular and the chamber 100 includes a radiant heatsource 106 disposed in an inside diameter of the substrate support 104.The radiant heat source 106 typically comprises a plurality of lamps.Examples of an RTP chamber that may be modified and a substrate supportthat may be used is described in U.S. Pat. No. 6,800,833 and UnitedStates Patent Application Publication No. 2005/0191044.

The RTP chamber 100 also includes a cooling block 180 adjacent to,coupled to, or formed in the top 112. Generally, the cooling block 180is spaced apart and opposing the radiant heat source 106. The coolingblock 180 comprises one or more coolant channels 184 coupled to an inlet181A and an outlet 181 B. The cooling block 180 may be made of a processresistant material, such as stainless steel, aluminum, a polymer, or aceramic material. The coolant channels 184 may comprise a spiralpattern, a rectangular pattern, a circular pattern, or combinationsthereof and the channels 184 may be formed integrally within the coolingblock 180, for example by casting the cooling block 180 and/orfabricating the cooling block 180 from two or more pieces and joiningthe pieces. Additionally or alternatively, the coolant channels 184 maybe drilled into the cooling block 180.

The inlet 181A and outlet 181B may be coupled to a coolant source 182 byvalves and suitable plumbing and the coolant source 182 is incommunication with the controller 124 to facilitate control of pressureand/or flow of a fluid disposed therein. The fluid may be water,ethylene glycol, nitrogen (N2), helium (He), or other fluid used as aheat-exchange medium.

In the embodiment shown, the substrate support 104 is optionally adaptedto magnetically levitate and rotate within the interior volume 120. Thesubstrate support 104 shown is capable of rotating while raising andlowering vertically during processing, and may also be raised or loweredwithout rotation before, during, or after processing. This magneticlevitation and/or magnetic rotation prevents or minimizes particlegeneration due to the absence or reduction of moving parts typicallyrequired to raise/lower and/or rotate the substrate support.

The chamber 100 also includes a window 114 made from a materialtransparent to heat and light of various wavelengths, which may includelight in the infra-red (IR) spectrum, through which photons from theradiant heat source 106 may heat the substrate 140. In one embodiment,the window 114 is made of a quartz material, although other materialsthat are transparent to heat and light may be used, such as sapphire.The window 114 may also include a plurality of lift pins 144 coupled toan upper surface of the window 114, which are adapted to selectivelycontact and support the substrate 140, to facilitate transfer of thesubstrate into and out of the chamber 100. Each of the plurality of liftpins 144 is configured to minimize absorption of energy from the radiantheat source 106 and may be made from the same material used for thewindow 114, such as a quartz material. The plurality of lift pins 144may be positioned and radially spaced from each other to facilitatepassage of an end effector coupled to a transfer robot (not shown).Alternatively, the end effector and/or robot may be capable ofhorizontal and vertical movement to facilitate transfer of the substrate140.

In one embodiment, the radiant heat source 106 includes a lamp assemblyformed from a housing which includes a plurality of honeycomb tubes 160in a coolant assembly (not shown) coupled to a coolant source 183. Thecoolant source 183 may be one or a combination of water, ethyleneglycol, nitrogen (N2), and helium (He). The housing walls 108, 110 maybe made of a copper material or other suitable material having suitablecoolant channels formed therein for flow of the coolant from the coolantsource 183. The coolant cools the housing of the chamber 100 so that thehousing is cooler than the substrate 140. Each tube 160 may contain areflector and a high-intensity lamp assembly or an IR emitter from whichis formed a honeycomb like pipe arrangement. This close-packed hexagonalarrangement of pipes provides radiant energy sources with high powerdensity and good spatial resolution. In one embodiment, the radiant heatsource 106 provides sufficient radiant energy to thermally process thesubstrate, for example, annealing a silicon layer disposed on thesubstrate 140. The radiant heat source 106 may further comprise annularzones, wherein the voltage supplied to the plurality of tubes 160 bycontroller 124 may be varied to enhance the radial distribution ofenergy from the tubes 160. Dynamic control of the heating of thesubstrate 140 may be affected by the one or more temperature sensors 117adapted to measure the temperature across the substrate 140.

In the embodiment shown, an optional stator assembly 118 circumscribesthe walls 108 of the chamber body 102 and is coupled to one or moreactuator assemblies 122 that control the elevation of the statorassembly 118 along the exterior of the chamber body 102. In oneembodiment (not shown), the chamber 100 includes three actuatorassemblies 122 disposed radially about the chamber body, for example, atabout 120° angles about the chamber body 102. The stator assembly 118 ismagnetically coupled to the substrate support 104 disposed within theinterior volume 120 of the chamber body 102. The substrate support 104may comprise or include a magnetic portion to function as a rotor, thuscreating a magnetic bearing assembly to lift and/or rotate the substratesupport 104. In one embodiment, at least a portion of the substratesupport 104 is partially surrounded by a trough (not shown) that iscoupled to a fluid source 186, which may include water, ethylene glycol,nitrogen (N₂), helium (He), or combinations thereof, adapted as a heatexchange medium for the substrate support. The stator assembly 118 mayalso include a housing 190 to enclose various parts and components ofthe stator assembly 118. In one embodiment, the stator assembly 118includes a drive coil assembly 168 stacked on a suspension coil assembly170. The drive coil assembly 168 is adapted to rotate and/or raise/lowerthe substrate support 104 while the suspension coil assembly 170 may beadapted to passively center the substrate support 104 within theprocessing chamber 100. Alternatively, the rotational and centeringfunctions may be performed by a stator having a single coil assembly.

An atmosphere control system 164 is also coupled to the interior volume120 of the chamber body 102. The atmosphere control system 164 generallyincludes throttle valves and vacuum pumps for controlling chamberpressure. The atmosphere control system 164 may additionally include gassources for providing process or other gases to the interior volume 120.The atmosphere control system 164 may also be adapted to deliver processgases for thermal deposition processes, thermal etch processes, andin-situ cleaning of chamber components.

The chamber 100 also includes a controller 124, which generally includesa central processing unit (CPU) 130, support circuits 128 and memory126. The CPU 130 may be one of any form of computer processor that canbe used in an industrial setting for controlling various actions andsub-processors. The memory 126, or computer-readable medium, may be oneor more of readily available memory such as random access memory (RAM),read only memory (ROM), floppy disk, hard disk, or any other form ofdigital storage, local or remote, and is typically coupled to the CPU130. The support circuits 128 are coupled to the CPU 130 for supportingthe controller 124 in a conventional manner. These circuits includecache, power supplies, clock circuits, input/output circuitry,subsystems, and the like.

In one embodiment, each of the actuator assemblies 122 generallycomprise a precision lead screw 132 coupled between two flanges 134extending from the walls 108 of the chamber body 102. The lead screw 132has a nut 158 that axially travels along the lead screw 132 as the screwrotates. A coupling 136 is coupled between the stator 118 and nut 158 sothat as the lead screw 132 is rotated, the coupling 136 is moved alongthe lead screw 132 to control the elevation of the stator 118 at theinterface with the coupling 136. Thus, as the lead screw 132 of one ofthe actuators 122 is rotated to produce relative displacement betweenthe nuts 158 of the other actuators 122, the horizontal plane of thestator 118 changes relative to a central axis of the chamber body 102.

In one embodiment, a motor 138, such as a stepper or servo motor, iscoupled to the lead screw 132 to provide controllable rotation inresponse to a signal by the controller 124. Alternatively, other typesof actuators 122 may be utilized to control the linear position of thestator 118, such as pneumatic cylinders, hydraulic cylinders, ballscrews, solenoids, linear actuators and cam followers, among others.

In embodiments that include the optional stator assembly 118, thechamber 100 may also include one or more sensors 116, which aregenerally adapted to detect the elevation of the substrate support 104(or substrate 140) within the interior volume 120 of the chamber body102. The sensors 116 may be coupled to the chamber body 102 and/or otherportions of the processing chamber 100 and are adapted to provide anoutput indicative of the distance between the substrate support 104 andthe top 112 and/or bottom 110 of the chamber body 102, and may alsodetect misalignment of the substrate support 104 and/or substrate 140.

The one or more sensors 116 are coupled to the controller 124 thatreceives the output metric from the sensors 116 and provides a signal orsignals to the one or more actuator assemblies 122 to raise or lower atleast a portion of the substrate support 104. The controller 124 mayutilize a positional metric obtained from the sensors 116 to adjust theelevation of the stator 118 at each actuator assembly 122 so that boththe elevation and the planarity of the substrate support 104 andsubstrate 140 seated thereon may be adjusted relative to and a centralaxis of the RTP chamber 100 and/or the radiant heat source 106. Forexample, the controller 124 may provide signals to raise the substratesupport by action of one actuator 122 to correct axial misalignment ofthe substrate support 104, or the controller may provide a signal to allactuators 122 to facilitate simultaneous vertical movement of thesubstrate support 104.

The one or more sensors 116 may be ultrasonic, laser, inductive,capacitive, or other type of sensor capable of detecting the proximityof the substrate support 104 within the chamber body 102. The sensors116, may be coupled to the chamber body 102 proximate the top 112 orcoupled to the walls 108, although other locations within and around thechamber body 102 may be suitable, such as coupled to the stator 118outside of the chamber 100. In one embodiment, one or more sensors 116may be coupled to the stator 118 and are adapted to sense the elevationand/or position of the substrate support 104 (or substrate 140) throughthe walls 108. In this embodiment, the walls 108 may include a thinnercross-section to facilitate positional sensing through the walls 108.

The chamber 100 also includes one or more temperature sensors 117, whichmay be adapted to sense temperature of the substrate 140 before, during,and after processing. In the embodiment depicted in FIG. 1, thetemperature sensors 117 are disposed through the top 112, although otherlocations within and around the chamber body 102 may be used. Thetemperature sensors 117 may be optical pyrometers, as an example,pyrometers having fiber optic probes. The sensors 117 may be adapted tocouple to the top 112 in a configuration to sense the entire diameter ofthe substrate, or a portion of the substrate. The sensors 117 maycomprise a pattern defining a sensing area substantially equal to thediameter of the substrate, or a sensing area substantially equal to theradius of the substrate. For example, a plurality of sensors 117 may becoupled to the top 112 in a radial or linear configuration to enable asensing area across the radius or diameter of the substrate. In oneembodiment (not shown), a plurality of sensors 117 may be disposed in aline extending radially from about the center of the top 112 to aperipheral portion of the top 112. In this manner, the radius of thesubstrate may be monitored by the sensors 117, which will enable sensingof the diameter of the substrate during rotation.

As described herein, the chamber 100 is adapted to receive a substratein a “face-up” orientation, wherein the deposit receiving side or faceof the substrate is oriented toward the top 112 and the “backside” ofthe substrate is facing the radiant heat source 106. The “face-up”orientation may allow the energy from the radiant heat source 106 to beabsorbed more rapidly by the substrate 140 as the backside of thesubstrate is sometimes less reflective than the face of the substratedepending on the processing involved (i.e., Ni coating). Typically, the“face-up” orientation, being unpatterned, presents a more uniformlyabsorbing face to the radiation source.

Although the cooling block 180 and radiant heat source 106 is describedas being positioned in an upper and lower portion of the interior volume120, respectively, the position of the cooling block 180 and the radiantheat source 106 may be reversed. For example, the cooling block 180 maybe sized and configured to be positioned within the inside diameter ofthe substrate support 104, and the radiant heat source 106 may becoupled to the top 112. In this arrangement, the quartz window 114 maybe disposed between the radiant heat source 106 and the substratesupport 104, such as adjacent the radiant heat source 106 in the upperportion of the chamber 100. Although the substrate 140 may absorb heatmore readily and does absorb radiant energy more uniformly when thebackside is facing the radiant heat source 106, the substrate 140 couldbe oriented in a face-up orientation or a face down orientation ineither configuration.

According to one or more embodiments, positioning of the substrate withrespect to the substrate support 104 is achieved by detection of thesubstrate position using a position sensor system 220 for sensing theposition of the substrate relative to the second substrate support, forexample, by detecting the edge of the generally planar substrate.Detection of the edge of the substrate can be accomplished in a varietyof ways. The examples discussed below are not intended to limit thescope of the invention. Other substrate position sensor systems 220 arewithin the scope of the invention. For example, the specific substrateposition sensor system may utilize an ultrasonic, laser, inductive,capacitive, or other type of sensor capable of detecting the position ofthe substrate relative to the substrate support.

Exemplary substrate position sensor systems 220 are described in detailin U.S. Pat. No. 7,153,185 (“the '185 patent”). An example of asubstrate position detection or sensor system 220 is shown in FIG. 2A. Alight source 225 to direct a light beam 227 onto a surface of thesubstrate 200, which is reflected as a reflected beam 229. A detector231 is positioned to monitor the intensity of light beam 229 reflectedfrom the substrate 200. One or both the detector 231 and the substrate200 may be moveable to provide relative motion between the detector 231and the substrate 200. The sensor system 220 may further include anelectronic controller 235 in communication with the detector, whereinthe controller 235 is operable to generate a plurality of measurementsfrom reflections detected by the detector 231.

The electronic controller 235 may include or be in communication with ageneral purpose programmable digital computer which receives the signalsfrom the optical sensor system. The measurements can then be associatedwith radial positions with the plane of the substrate using a Cartesianx-y coordinate system.

Through an algorithm and/or empirically determined measurements, theelectronic controller 235 can calculate a location on the substratesurface where a reflection occurred. Based on the nature of thereflection from the substrate surface, the controller may determinewhich of the measurements corresponds to an edge of the substrate. Thismay be determined by detecting a weak reflection from the substrate orno reflection at all. While the sensor system 220 is shown as beingpositioned below the substrate, it will be appreciated that thecomponents may be advantageously positioned above the substrate, so asnot to interfere with radiation delivered by the lamps or other heatingelements to heat the substrate. In addition, the components of thesensor system 220 should be positioned to avoid interfering with thelight pipes and temperature detection system which may includepyrometers.

Specific implementations of system 220 can include one or more of thefollowing features. The light beam 227 can have a spot size of less thanabout one millimeter on the surface of the substrate. The system canfurther include a beam focusing optic including include a refractiveoptical element (e.g., a lens), a reflective optical element (e.g., amirror), a diffractive optical element (e.g., a grating), and/or aholographic optical element (e.g., a holographic grating). The apparatuscan further include a collimating optic positioned to collimate lightreflected from the substrate surface prior to the reflected light beingdetected by the detector.

In another embodiment of an optical detector system, shown in FIG. 2B,an optical detection system may include a light source and detector 252and is configured to evaluate a shadow cast by either the secondsubstrate support on the substrate or the substrate on the secondsubstrate support to detect the position of the substrate relative tothe position of the second substrate support. In the embodiment shown inFIG. 2B, it will be apparent that detector 252 is positioned to detect ashadow on the substrate 200 cast by the substrate support (edge ring)206. It will be appreciated that the light source 250 and detector 252could be positioned above the substrate 200 and substrate support 206 todetect a shadow cast by the substrate 200 on the substrate support 206.

In another variant of an optical detection system the light source orother suitable illumination system 250 can cooperate with detector 252,which may be a camera, which is communication with a vision analysissystem 254. Vision analysis system 254, which may include empirical dataand/or lookup tables and include a general purpose computer can be usedto detect the centers of the substrate support 206 and the substrate200.

Each of the optical systems described above, or any other suitablemethod for detecting or sensing the relative positions of the substrateand the wafer support can be used together with a system for moving oneor both of the substrate support and the substrate. Exemplaryembodiments of such systems will be described further below.

The individual components of the position sensor systems 220 describedabove may be mounted in the top or lid 112 of the processing chamber.The sensor components may be positioned in different locations along theX and Y axis of the chamber to assist in detecting the center positionof the wafer. Alternatively, the components of the sensor system 220 maybe placed in the sidewalls of the processing chamber.

FIGS. 3A and 3B also show embodiments of positioning mechanisms. In FIG.3A, the substrate 200 is loaded into the chamber on the loading blade202 (also called a robot blade 202). A plurality of lift pins 204 mayprotrude through the reflector plate 214 and lift the substrate 200 offof the loading blade. This may be accomplished by positioning the liftpins on the outer periphery of the reflector plate 214, and minimizingthe planar area of the robot blade 202 so that edges of the substrate200 overhang at least a portion of the robot blade 202 to allow the liftpins to contact outer peripheral edges of the substrate to lift thesubstrate off of the robot blade 202. Thus, the robot blade 202 mayextend through and between the extended lift pins 204, enabling therobot blade 202 to retract after the pins 204 have lifted the substrate200 off the robot blade 202. In another variant, the robot blade 202 mayhave slots or cutouts (not shown) in preselected locations that alignwith the locations of the lift pins to lift the substrate off of therobot blade. Suitable ways of achieving lift off of the substrate fromthe robot blade can be found in U.S. Pat. Nos. 6,722,834 and 6,709,218.The holes in the reflector plate 214 are enlarged, allowing the pins tomove within the same X-Y plane 210 as the substrate support in the formof an edge ring 206 as well as in a direction perpendicular (shown byarrow 212) to the edge ring 206. The loading blade 202 can then bewithdrawn from the chamber. The substrate position sensor system candetermine the particular adjustments required to move the substrate 200position into a pre-selected position, which may be determinedempirically in advance. The pre-selected orientation is an orientationin which the substrate 200 is centered with respect to the chambercenter, which may be determined by the relative position of thesubstrate to the substrate support 206 in an X-Y plane. Generally, ifthe substrate support 206 is centered with respect to the chambercenter, when the substrate 200 and substrate support 206 are in acentered orientation, the substrate 200 should be centered in thechamber. The lift pins 204 can then move within the enlarged holes 208in the reflector plate 214 until the substrate 200 is coaxial with theedge ring 206. Once the substrate 200 is in the desired position, thelift pins 204 can retract, lowering the substrate 200 to the edge ring206, as shown in FIG. 3B. While it may be desired, holes do not need tobe drilled or sculpted in the edge ring 206 as the lift pins 204 do notintersect the edge ring 206.

Alternatively, the lift pins 204 may be stationary in the reflectorplate 214. The reflector plate can then move within the same plane 210as the edge ring 206 as well as perpendicular 212 to the edge ring 206.Allowing the substrate 200 to be positioned on the edge ring 206.

FIG. 3C shows a cross sectional view of the edge ring 206 and reflectorplate 214. It can be seen that the holes 208 in the reflector plate 214are larger than the diameter of the lift pins 204. This allows the liftpins 204 to move in three-dimensions to adjust the position of asubstrate.

FIG. 4 shows an exemplary embodiment of a chamber utilizing apositioning mechanism. The substrate 302 is loaded into the chamber 300on a loading blade 318 through opening 320, and the loading blade 318supporting the substrate 320 remains in the chamber until an optimalposition is obtained as described below. A substrate position sensorsystem 304 (for example, of the type described in above) can determineif adjustments are necessary to the position of the substrate 302 withrespect to the second substrate support 306, which is shown as an edgering which supports the substrate at the edges of the substrate 302. Acomputer or other suitable processor in communication with the substrateposition sensor system 304 and in communication with a positioningmechanism can then be used to adjust the position of the substrate 302with respect to the substrate support 306. The adjustments to the edgering 306 can be made by applying directional force using a radialpositioning mechanism that includes pushers 310 that push or move theedge ring 306 in the desired radial direction. Alternatively, a pusher310 can apply a directional force to the magnetically levitating rotor308 to move the substrate support 306 in the desired direction. Once thesubstrate support 306 is positioned coaxially with the substrate 302,the lift pins 312 lift the substrate 302 from the loading blade. Afterthe loading blade is removed, the lift pins 312 can then lower thesubstrate 302 to the substrate support 306 resulting in coaxiallyaligned substrate support 306 and substrate 302.

Movement of the edge ring or the magnetically levitated rotor byapplication of directional force can be accomplished in various otherways. Non-limiting examples of radial positioning mechanisms include aseries of positioning rods 310 which push the edge ring 306 or rotor308; jets of gas or liquid to push the edge ring or rotor; orapplication of a magnetic field using the stator to cause the edge ring306 or rotor 308 to move. Any suitable pusher mechanisms, such as screwactivated, hydraulically activated or pneumatically activated pushermechanisms may be used to drive the positioning rods 310.

In another embodiment, as shown in FIG. 5, the substrate 402 is loadedinto the chamber 400 on the loading blade 404. A substrate positionsensor system 406 (for example, of the type described above) candetermine the necessary adjustments to coaxially locate the substrate402 and edge ring 408. The loading blade 404 can be moved by pushingmechanisms 410 or by motors 412 in communication with the substrateposition sensor system 406 via a processor or computer to position thesubstrate 402. Lift pins 414 lift the substrate 402 from the loadingblade 404. Upon removal of the loading blade 404, the lift pins 414 canlower, thereby depositing the substrate 402 onto the edge ring 408 in acoaxial relationship.

In a further embodiment, shown in FIG. 6, the substrate 502 is broughtinto the chamber 500 on the loading blade 504. A substrate positionsensor system 506 of the type described above determines the necessaryadjustments needed to place the substrate 502 and edge ring 508 in acoaxial relationship. The substrate position sensor system is incommunication with a processor or computer and a positioning mechanism.The substrate 502 is then pushed into position using a positioningmechanism selected from one or more of motor driven positioning rods,hydraulic or pneumatic positioning rods, liquid or gas jets, or othersimilar means 510, while the substrate 502 is on the loading blade 504.These positioning mechanisms can even be located on the blade itself.Once aligned, the lift pins 512 lift the substrate 502 off of theloading blade 504. The loading blade 504 retracts and the lift pins 512lower the substrate 502 onto the edge ring 508 in a coaxialrelationship.

In another embodiment, shown in FIG. 7, the substrate 600 can becoaxially aligned with the edge ring 602 while the substrate 600 is onthe lift pins 604. In these embodiments, the substrate 600 can be pushedfrom the side by any suitable means, including, but not limited to,motor driven positioning rods 606, hydraulic or pneumatic drivenpositioning rods and/or pressure from gas or liquid jets through nozzles608. Once aligned, the lift pins 604 retract, lowering the substrate 600to the edge ring 602 in a coaxially aligned relationship.

Further embodiments, shown in FIGS. 8A and 8B, allow for the coaxialalignment of the substrate 700 with the edge ring 702 after thesubstrate 700 has been placed on the edge ring 702. This alignment canbe accomplished by any suitable means, including, but not limited to,motor driven positioning rods 704, hydraulic or pneumatic drivenpositioning rods or pressure from gas or liquid jets through nozzles706. Once coaxially aligned with the edge ring 702, the substrate 700 isready to be processed.

The apparatus of one or more detailed embodiments is capable ofaccurately and reproducibly positioning the edge ring and substratewithin about ±0.005 inches of being coaxial. In more detailedembodiments, the substrate and edge ring are positioned to be withinabout ±0.002 inches of being coaxial, or within about ±0.001 inches ofbeing coaxial.

Accordingly, one or more embodiments of the invention are directed torapid thermal processing apparatus for processing a substrate. Theapparatus comprises a chamber including a heat source. The apparatusincludes first substrate support, typically in the form of lift pins ora robot blade, for holding the substrate in the chamber in a firstposition and a second substrate support, for example, an edge ring, forholding the substrate in a second position. The second substratesupport, which in specific embodiments comprises an edge ring thatsupports the substrate at its edges, is adapted to hold the substrateduring thermal processing and being moveable in a direction to place thesubstrate closer and further from the heat source. A sensor system forsensing the axial position of the substrate is included. The sensorsystem communicates with an actuator which operates to cause the axialposition of the substrate relative to the axial position of the secondsubstrate support to be changed. The first substrate support may act as,and be referred to as a temporary substrate support.

FIG. 9A is a top view of one embodiment of a substrate support 900. FIG.9B is a cross sectional view of the substrate support 900. The substratesupport 900 is formed from the assembly of multiple parts comprising anedge ring 910, a support ring 920, and a support cylinder 930. The edgering 910 has an annular shape that facilitates the placement of asubstrate 902. As shown in FIG. 9B, the edge ring 910 includes an outersurface 912 and an inner surface 914 parallel to and recessed from theouter surface 912. The outer surface 912 is thereby located at a levelhigher than the inner surface 914, which has an outer border delimitedby a sidewall 915. The sidewall 915 may be slightly higher than thethickness of the substrate 902 to facilitate its placement on the innersurface 914. The edge ring 910 may also include an outer flange 916 thatextends downward from the outer surface 912. A gap 918 is definedbetween an outer flange 916 and a sidewall 915 to facilitate theassembly of the edge ring 910 on the support ring 920. In oneembodiment, the edge ring 910 may be simply disposed on the support ring920 without attachment for easy removal and replacement. In detailedembodiments, the second substrate support may be a thin solid recesseddisk.

The support ring 920 comprises a thin flat section with an inner flange922 extending upward and an outer flange 924 extending downward. Theinner flange 922 extending upward is coupled to the outer flange 916 ofthe edge ring 910. The outer flange 924 extending downward is coupled tothe support cylinder 930. The support cylinder 930 provides verticalsupport to the support ring 920. As shown in FIG. 9A, a bottom 932 ofthe support cylinder 930 may comprise an indented profile that allowsfor air flow into the support cylinder 930.

An alternative embodiment of the edge ring 910 is illustrated in FIG.9C. In this embodiment, the inner surface 914 may also include analignment mark 919 that may be used to as reference for facilitating thealignment of a corresponding alignment mark 904 provided on thesubstrate 902. In one embodiment, the alignment mark 919 on the innersurface 914 may be a formed as a protrusion, and the alignment mark 904on the rim of the substrate 902 may be a notch. Proper alignment andorientation of the substrate 902 on the edge ring 910 may therebyprevent uneven heat distribution owing to light leakage, and improvethermal transfer.

As shown in the top view of FIG. 10A and side view of FIG. 10B, positionsensors 1014 and 1016 may also be used to ensure that a substrate 1002is properly centered relative to an edge ring 1003 of the substratesupport 1004 within a processing chamber 1001. In one embodiment, theposition sensors 1014 and 1016 may be placed above the substrate support1004, for example by mounting the position sensors 1014 and 1016proximate to the chamber lid. The position sensors 1014 and 1016 mayinclude ultrasonic sensors, optical sensors, inductive sensors,capacitive sensors, or other type of position sensors capable ofdetecting a distance between an edge 1006 of the substrate 1002 and asidewall 1005 of the edge ring 1003. In another embodiment, the positionsensors 1014 and 1016 may emit light beams to detect any impropercentering of the substrate 1002 relative to the edge ring 1003.

As shown in FIG. 10B, the substrate 1002 may be placed on the edge ring1003 by lowering support pins 1007. To supply the substrate 1002 with auniform thermal treatment across the substrate surface, the substrate1002 may be positioned on the center of the edge ring 1003. The edgering 1003 may be adjusted to meet the substrate 1002 by moving thesubstrate support 1004 in the direction of an X and a Y axis. To findthe center position of the edge ring 1003 for the substrate 1002 to bepositioned, the position sensors 1014 and 1016 may be positioned indifferent locations to help detect for the center position. In oneembodiment, position sensors 1014 may be mounted on the chamber lid 1015relative to a spot between edge 1006 of the substrate 1002 and sidewall1005 of the edge ring 1003 as shown in FIG. 10B. In each spot is adistance 1008 between edge 1006 of the substrate 1002 and sidewall 1005of the edge ring 1003. Each spot may correspond to an axis and adistance relative to the specific axis. For example, the spot forposition sensor 1014 may correspond to the X axis and the spot forposition sensor 1016 may correspond to the Y axis. Each spot may containa distance 1008 which may be measured by the position sensors 1014 and1016. In one embodiment, the position sensors 1014 and 1016 may emit alight beam 1011 to detect for the distance 1008 within the spot. Inanother embodiment, the reflective light beam 1011 may be a round spotor a line. In yet another embodiment, the spot size of the round spot orthe line may be no less than 4.5 mm. In still another embodiment, thereflective light beam 1011 may be transmitted within a range from about25-50 mm. The distance 1008 measured at each spot may be compared tofind a theta adjustment value. In one embodiment, the accuracy for thedistances measured may have a range of about ±10 μm or better. The thetaadjustment value contains an adjustable distance for the X axis and anadjustable distance for the Y axis. The adjustable distances areadjustments required for the edge ring 1003 to be moved into the centerposition in the X and Y axis. After the theta adjustment value has beenobtained, the edge ring 1003 may then be adjusted to move to a properposition. Signal then may be sent to the robotic arm to pick up thesubstrate 1002 from the support pins 1007 and transfer the substrate1002 to a proper position on the substrate support 1004 for thermaltreatment. In one embodiment, the distance from the substrate to theedge ring has a range of about 0 to 4.342 mm. In a specific embodiment,the distance from the substrate to the edge ring is at about 2.171 mm.In detailed embodiments, the theta adjustment value is associated withadjustment information relating to a Z position which may be adjustedthrough vertical movement.

FIG. 10C is a top view of a substrate support 1052 within a processingchamber 1050 according to another embodiment of the invention.Alternatively, the distance 1008 between the edge ring 1056 and thesubstrate 1054 may also be measured by placing the sensors at the innersidewalls of the processing chamber 1050. In one embodiment, a firstlight transmitter 1068 may be coupled to one side of the inner sidewall,and a first light receiver 1070 may be coupled to a sidewall adjacent tothe sidewall where the first light transmitter 1068 is positioned tomeasure for a distance 1058 that corresponds to the X axis. A secondlight transmitter 1072 may be coupled to another inner sidewall, and asecond light receiver 1074 may be coupled to a sidewall adjacent to theinner sidewall where the second light transmitter 1072 is positioned tomeasure for a distance 1059 that corresponds to the Y axis. Thedistances 1058 and 1059 may be measured by light beams 1076 transmittedby the light transmitters 1068 and 1072 through a light pipe 1078. Thelight beams 1076 may pass through distances 1058 and 1059 between theedge ring 1056 and the substrate 1054, and may be received by the lightreceivers 1070 and 1074. After distances 1058 and 1059 have beenobtained and send back to system controller 1124, theta adjustment valuemay now be calculated and the edge ring 1003 may then be adjustedaccording to the theta adjustment value by moving in the direction of Xand Y axis to a center position where the substrate may be positionedin.

FIG. 11 shows a simplified isometric view of a detailed embodiment of arapid thermal processing chamber 1100. The processing chamber 1100includes the components described with respect to FIG. 1, and thereference numerals are consistent for the equivalent components. Thechamber 1100 includes one or more sensors 116, which are generallylocated outside the chamber and adapted to detect the elevation of thesubstrate support 104 (or substrate 140) within the interior volume 120of the chamber body 102. The sensors 116 may be coupled to the chamberbody 102 through tubular ports as shown and/or other portions of theprocessing chamber 1100 and are adapted to provide an output indicativeof the distance between the substrate support 104 and the top 112 and/orbottom 110 of the chamber body 102, and may also detect misalignment ofthe substrate support 104 and/or substrate 140. In another embodiment(not shown), the sensors 116 can be placed inside the stator housing1190, which would allow the sensors 316 to move with the stator 118 upand down. This embodiment would permit the sensors 116 to obtain areference point on the ring section 192. In such an embodiment, thesignal would likely be constant and would look for a deviation of thesignal, and vertical position could be determined from feedback from themotor 138.

The one or more sensors 116 are coupled to the controller 124 thatreceives the output metric from the sensors 116 and provides a signal orsignals to the one or more actuator assemblies 122 to raise or lower thesubstrate support 104. The controller 124 may utilize a positionalmetric obtained from the sensors 116 to adjust the elevation of thestator 118 at each actuator assembly 122 so that both the elevation andthe planarity of the substrate support 104 and substrate 140 seatedthereon may be adjusted relative to the central axis of the chamber 100and/or the radiant heat source 106. For example, the controller 124 mayprovide signals to raise the substrate support by action of the actuator122 to correct axial misalignment of the substrate support 104, or thecontroller may provide a signal to all actuators 122 to facilitatesimultaneous vertical movement of the substrate support 104.

The sensors 116 may be coupled to the walls 108, although otherlocations within and around the chamber body 102 may be suitable, suchas coupled to the stator 118 outside of the chamber 1100. In oneembodiment, one or more sensors 116 may be coupled to the stator 118 andare adapted to sense the elevation and/or position of the substratesupport 104 (or substrate 140) through the walls 108. In theseembodiments the walls 108 may include a thinner cross-section tofacilitate positional sensing through the walls 108.

The substrate support 104 of FIG. 11 includes an annular body 1191having an inside diameter sized to receive the radiant heat source 106and other hardware (not shown). The substrate support 104 is at leastpartially comprised of a magnetic ring section 1192 and a supportsection 1194. The magnetic ring section 1192 may be at least partiallycomprised of a magnetic material, such as a ferrous containing material,to facilitate magnetic coupling of the substrate support 104 to thestator 118. The ferrous containing material includes low carbon steel,stainless steel, which may include a plating, such as nickel. In oneembodiment, the magnetic ring section 1192 is comprised of a pluralityof permanent magnets disposed in a polar array about a central axis. Themagnetic ring section 1192 may additionally include an outer surfacehaving one or more channels formed therein. In one embodiment, themagnetic ring section 1192 includes a shaped profile, such as an “E”shape or a “C” shape having one or more channels formed therein.

According to one or more embodiments, it is possible to center thesubstrate 140 on the edge ring 104 by adjusting the position of themagnetically levitated substrate support 104 so it is co-axial with thesubstrate 140 on the lift pins 144 before lifting the substrate 140. Afeedback system including a set of optical sensors 116 or a visionsystem in communication with the system controller 124 can be used toachieve centering of the substrate. Placement of the substrate 140 couldbe done using feedback from such system. The stator 118 can be used tocenter the edge ring 104 beneath the substrate 140 to with highprecision, for example, 0.001″ or better, and can compensate for up to0.010″ of displacement.

One or more embodiments of the invention have a robot (not shown) whichbrings the substrate 140 into chamber 1100, where it is transferred ontothe lift pins 144. The substrate support 104 is centered beneath thesubstrate 140 using variable magnetic fields generated by the stator118, which changes the position of the substrate support in the chamberthe substrate support 104. FIG. 12 shows a top view of an embodiment ofthe stator assembly 118 with the housing removed. The magnetic fieldstrength of a series of electromagnets 1200, which are in communicationwith the system controller, can be adjusted to create an electromagneticbias, which can push/pull a substrate support within the chamber. Atleast one electromagnet can be biased to push the substrate support, andat least one electromagnet can be biased to pull the substrate support.By adjusting the strength of the magnetic field of the electromagnets1200 located at various locations around the stator 118, the substratesupport can be accurately positioned. Sensors 1202, which can be eddycurrent sensors, in communication with the system controller 124 can beemployed to detect the position of the substrate support within thechamber, thereby providing feedback in the form of position signals tothe system controller 124. The feedback from these sensors 1202 can beevaluated by the system controller 124, which, in turn can provide asignal to bias one or more of the electromagnets to adjust the positionof the substrate support.

FIG. 12 shows the electromagnets 1200 and sensors 1202 located atpositions approximately 120° apart. This is illustrative only, andshould not be taken as limiting the invention. Any suitable number ofsensors and electromagnets can be employed. For example, sixelectromagnets can be controlled by the system controller 124 withfeedback originating from three sensors.

Further embodiments of the invention are directed to methods ofprocessing a substrate. The method comprises transferring a substrateinto a processing chamber. The substrate is transferred to anintermediate substrate support, which may be, for example, a set of liftpins. The location of the substrate is determined, for example bydetecting one or more substrate edges. The position of the substraterelative to a substrate support is adjusted so that the substrate andthe substrate support are aligned in a preselected relative orientation.The substrate position sensor system communicates through a centralprocessing unit, for example, a general purpose computer, with thepositioning mechanism, which makes the desired adjustment of to theposition of the substrate relative to the substrate support. A feedbackcontrol system can be used to ensure that the relative position of thesubstrate and the substrate support is optimized until the substrate andsubstrate support are in substantial coaxial alignment. The substrate istransferred to the second substrate support, which may be an edge ring.The substrate is then ready to be processed. The prescribed relativeorientation may be axial alignment of the substrate with the edge ring,or alignment of the substrate with the edge ring based on an empiricallydetermined position. For example, the empirically determined positionmay not align the substrate and edge ring coaxially, but may align thethermal center of mass of the substrate with the center of the edgering.

The substrate may be transferred into the processing chamber using arobot blade. The intermediate support may be a plurality of lift pinslocated on a lift pin assembly. Other methods of introducing thesubstrate to the chamber and providing intermediate support are alsowithin the scope of this invention.

The order of these steps varies depending on the particular embodimentof use and should not be taken as a strict procedural sequence. In someembodiments, the relative position of the substrate with respect to theedge ring is adjusted prior to transferring the substrate onto the liftpins. In other embodiments, the relative position with respect to theedge ring is adjusted after transferring the substrate to the lift pins.In various embodiments, the relative position of the substrate withrespect to the edge ring is adjusted by changing one or more of thelocation of the substrate, the location of the edge ring or the locationof the lift pins.

Detailed embodiments are directed to methods for concentric positioningof a substrate on a levitating substrate support. A substrate istransferred into a processing chamber and placed onto a temporarysupport element. The substrate position relative to a substrate supportis measured using sensors. The position of the substrate support isadjusted to bring the substrate support into concentric alignment withthe substrate. The substrate is transferred from the temporary supportelement to the substrate support.

In specific embodiments, concentric positioning of the substrate on thesupport comprises biasing at least one magnet to pull the substratesupport or push the substrate support.

Further specific embodiments are directed to a substrate processingapparatus comprising a chamber, a substrate support, a position sensorand a system controller. The substrate support is disposed in thechamber and comprises an annular body configured to support thesubstrate on an upper surface thereof. The substrate support ismagnetically coupled to a plurality of electromagnets disposed adjacentthe substrate support. The position sensor can detect the substrateposition relative to the substrate support. The system controller is incommunication with the electromagnets and is operative to bias at leastone of the electromagnets to move (i.e., push or pull) the substratesupport relative to the substrate.

Reference throughout this specification to “one embodiment,” “certainembodiments,” “one or more embodiments” or “an embodiment” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe invention. Thus, the appearances of the phrases such as “in one ormore embodiments,” “in certain embodiments,” “in one embodiment” or “inan embodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the invention.Furthermore, the particular features, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present invention without departing from the spirit andscope of the invention. Thus, it is intended that the present inventioninclude modifications and variations that are within the scope of theappended claims and their equivalents.

1. A method of processing a substrate, comprising: transferring a planarsubstrate having an edge into a processing chamber onto an intermediatesubstrate support; determining the location of the edge of thesubstrate; adjusting the position of the substrate relative to a secondsubstrate support so that the substrate and the second substrate supportare in substantially axial alignment; transferring the substrate to thesecond substrate support; and thermally processing the substrate.
 2. Themethod of claim 1, wherein determining the location of the edge of thesubstrate comprises: directing light onto a surface of the substrate;and measuring an intensity of light reflected from the surface of thesubstrate.
 3. The method of claim 1, wherein determining the location ofthe edge of the substrate comprises: directing light at one of thesubstrate to create a shadow of the substrate on the second substratesupport and the second support to create a shadow of the second supporton the substrate; and determining the position of the substrate relativeto the second support from the shadow.
 4. The method of claim 1, whereinthe substrate is transferred into the processing chamber on a robotblade, the intermediate substrate support comprises lift pins.
 5. Themethod of claim 4, wherein the relative position of the substrate withrespect to the second substrate support is adjusted prior totransferring the substrate onto the lift pins.
 6. The method of claim 4,wherein the relative position of the substrate with respect to thesecond substrate support is adjusted after transferring the substrateonto the lift pins.
 7. The method of claim 1, wherein the relativeposition of the substrate with respect to the second substrate supportis adjusted by changing one or more of the location of the substrate,the location of the second substrate support or the location of theintermediate substrate support.
 8. The method of claim 1, furthercomprising transmitting a reflective light beam from one sensor througha space between the substrate and the substrate support to determine atheta adjustment value for placing the substrate onto a center positionof the second substrate support.
 9. The method of claim 8, wherein oneor more sensors in communication with a control system in communicationwith a plurality of magnets adjacent the substrate support adjust theposition of the second substrate support by applying one or moremagnetic fields adjacent the substrate support in response to a positionobtained by a sensor.
 10. The method of claim 9, wherein the thetaadjustment value is determined by measuring a distance from at least twopositions X and Y between the second substrate support and the substrateand at least two sensors are used to determine the distance from the atleast two positions X and Y for the theta adjustment.
 11. The method ofclaim 1, wherein the position of the second substrate support relativeto the substrate is adjusted by generating or modulating one or moremagnetic fields adjacent the second substrate support.
 12. The method ofclaim 1, wherein the position of the second substrate support relativeto the substrate is adjusted using one or more of a plurality ofpositioning rods to contact the edge of the substrate or the substratesupport, a plurality of liquid or gas jets positioned adjacent one ormore of the substrate and the second substrate support.
 13. A method ofprocessing a substrate, comprising: transferring a planar substratehaving an edge into a processing chamber onto an intermediate substratesupport; transmitting a reflective light beam from one sensor through aspace between the substrate and the substrate; determining a thetaadjustment value for axially aligning the substrate relative to thesecond substrate support; adjusting the position of the substraterelative to a second substrate support using the theta adjustment valueso that the substrate and the second substrate support are substantiallyin axial alignment; transferring the substrate to the second substratesupport; and thermally processing the substrate.
 14. The method of claim13, wherein determining the determining the theta adjustment valuecomprises measuring a distance from at least two positions X and Ybetween the second substrate support and the substrate and determiningthe distance from the at least two positions X and Y.
 15. The method ofclaim 13, wherein the position of the substrate relative to the secondsubstrate support is adjusted prior to transferring the substrate ontothe intermediate substrate support.
 16. The method of claim 13, whereinthe position of the substrate relative to the second substrate supportis adjusted after transferring the substrate onto the intermediatesubstrate support.
 17. The method of claim 13, wherein adjusting theposition of the substrate relative to the second substrate supportcomprises moving one or more of the substrate, the intermediatesubstrate support and the second substrate support.
 18. A method ofprocessing a substrate, comprising: transferring a planar substratehaving an edge into a processing chamber onto an intermediate substratesupport; directing light at one of the substrate and a second substratesupport, so that light directed at the substrate will cast a shadow onthe substrate support or light directed at the second substrate supportwill cast a shadow on the substrate; determining the position of thesubstrate relative to the second substrate support using the shadow;adjusting the position of the substrate relative to the second substratesupport so that the substrate and the second substrate support are insubstantially axial alignment; transferring the substrate to the secondsubstrate support; and thermally processing the substrate.
 19. Themethod of claim 18, wherein the position of the substrate relative tothe second substrate support is adjusted prior to transferring thesubstrate onto the intermediate substrate support.
 20. The method ofclaim 18, wherein the position of the substrate relative to the secondsubstrate support is adjusted after transferring the substrate onto theintermediate substrate support.